Opioids and the skin: "itchy" perspectives beyond analgesia and abuse.

Opioids are intimately linked to central pain inhibition and their abuse potential. Thus, peripheral opioid receptors in the skin have been studied initially with a focus on their peripheral analgesic properties. Recent results, however, clearly indicate that opioids play a specific role in skin homeostasis by modulating keratinocyte differentiation, wound healing, and inflammatory responses.